Search found 3249 matches

by Lebowski
Aug 08 2011 8:45am
Forum: Motor Technology
Topic: Re-wind of a turnigy 80/100 (Now-tutorial w/Video)
Replies: 421
Views: 80267

Re: Re-wind of a turnigy 80/100 (Now-tutorial w/Video)

Hello! I'm a first time poster here but have been reading this forum for quite a while now (and specially the non-hub and motor technology sub-fora) I was wondering if anyone had tried rewinding a turnigy with copper foil instead of wire. Something like 0.1mm thick and as close to 16mm wide as poss...
by Lebowski
Aug 04 2011 2:07am
Forum: Motor Technology
Topic: Inductance What is it what does it do? Collosus has 8uH!
Replies: 308
Views: 30442

Re: Inductance What is it what does it do? Collosus has 8uH!

IN fact I tell you what I will wind it in such a way that I test the same lengh of wire with 3 turns with one and two strands.... So I will still have the two peices of wire hooked to the meter with one set of turns or 2 parallel sets of turns. What I would do is make two measurements, both with th...
by Lebowski
Aug 04 2011 1:31am
Forum: Motor Technology
Topic: Inductance What is it what does it do? Collosus has 8uH!
Replies: 308
Views: 30442

Re: Inductance What is it what does it do?

OK SOOOOOOOOOOOOOOOOOOOOOOOOOOOO BIIIIIIIIIIGGGGGGGGGGG NEEEEEEEEEEWWWWWWWWWS. Collossus has such low inductance it midas well not have any (well ok almost) I got the first cheep inductance meter today and here is some findings.... OH BTW you guys rewinding motors that are hard to control you would...
by Lebowski
Aug 04 2011 1:13am
Forum: Motor Technology
Topic: Inductance What is it what does it do? Collosus has 8uH!
Replies: 308
Views: 30442

Re: Inductance What is it what does it do?

OK SOOOOOOOOOOOOOOOOOOOOOOOOOOOO BIIIIIIIIIIGGGGGGGGGGG NEEEEEEEEEEWWWWWWWWWS. Collossus has such low inductance it midas well not have any (well ok almost) I got the first cheep inductance meter today and here is some findings.... OH BTW you guys rewinding motors that are hard to control you would...
by Lebowski
Aug 04 2011 1:01am
Forum: General Discussion
Topic: I'd like to go to college for electrical engineering
Replies: 23
Views: 1785

Re: I'd like to go to college for electrical engineering

I'm also an EE, I studied analog circuit design for implementation on IC's. For work I make things like ADC's for radio signals or DAC's with integrated amplifier for headphones. I like to think I'm very good at my job, I'm the top engineer at my site of work, I presented papers at international con...
by Lebowski
Aug 03 2011 5:46am
Forum: E-Bike Technical
Topic: I'm uncertain about the efficiency of Geared vs Direct Drive
Replies: 14
Views: 1581

Re: I'm uncertain about the efficiency of Geared vs Direct D

for a radial fluxm motor with no iron core: P_loss/P_usefull is proportional to 1 / (engine_rpm)^2 And with engine I mean the magnet/coil bits. But also P_loss/P_usefull is proportional to 1 / engine volume So.... it all depends :) a geared motor is typically build to a smaller form factor but runs ...
by Lebowski
Jul 27 2011 1:15am
Forum: E-Bike Technical
Topic: Converting a cargo tricycle (bakfiets)
Replies: 29
Views: 3521

Re: Converting a cargo tricycle (bakfiets)

Hoi bakfiets, ook een Nederlander ? Engine speed is a big factor regarding the efficiency of an engine. With 'engine speed' I mean the speed of the magnet/coil bits. It's a quadratic relation so 2 times the speed reduces the losses to 1/4. This is why hub motors are in general a bad idea if you go s...
by Lebowski
Jul 21 2011 2:02am
Forum: Motor Technology
Topic: My homemade bicycle motor, version 1
Replies: 8
Views: 4797

My homemade bicycle motor, version 1

Since I was pulling apart my motor anyway I thought I'd make some pictures to show how it's built. The motor is meant to power a bicycle. Here in Switzerland the limit for electric bikes is 250 W, above that it doesn't count as a bicycle anymore and it gets messy in the legal department (you need a ...
by Lebowski
Jul 20 2011 3:58am
Forum: E-Bike Technical
Topic: Excess current draw.
Replies: 19
Views: 2002

Re: Excess current draw.

Maybe the iron in your motor is saturating ? This would cause a sudden drop in winding inductance (which in turn leads to a sharp current increase)...
by Lebowski
Jul 20 2011 3:13am
Forum: Battery Technology
Topic: watt hours in series vs parallel - discuss
Replies: 17
Views: 1959

Re: watt hours in series vs parallel - discuss

Ok, I see your point, my reply was based on two different motors (the 100V one having 4 times more windings as the 25V one to
achieve same rpm, based on the simple PWM controllers everyone seems to use)
by Lebowski
Jul 20 2011 1:41am
Forum: Battery Technology
Topic: watt hours in series vs parallel - discuss
Replies: 17
Views: 1959

Re: watt hours in series vs parallel - discuss

Interestingly, the phase current only depends on the rate the motor is spinning and the power entering it. So, your 100v pack and your 25v pack both dumping 500w into the motor at the same speed both are placing exactly the same phase current on the motor and need the same size wires. The higher vo...
by Lebowski
Jul 08 2011 10:58am
Forum: Motor Technology
Topic: Agni motor tuning and racing
Replies: 123
Views: 24177

Re: Agni motor tuning and racing

Ok I get your argument regarding that the speeds (or to put it better: the pwm dutycycle) of the two controllers must match... How about splitting the output MOS transistors down the middle ? Example: lets say your controller has 6 MOS transistors in parallel capable of supplying enough current for ...
by Lebowski
Jul 08 2011 10:47am
Forum: E-Bike General Discussion
Topic: So, I pitched the idea of E-bikes to the local bicycle cops
Replies: 73
Views: 4795

Re: So, I pitched the idea of E-bikes to the local bicycle c

I bet you the police said something in the order of: "OK dude so you want to provide the local kids with fast e-bikes so us bicycle cops can no longer catch them ?"

followed by a good beating :mrgreen: jailtime :shock: sodomy :|
by Lebowski
Jul 08 2011 7:45am
Forum: Motor Technology
Topic: Agni motor tuning and racing
Replies: 123
Views: 24177

Re: Agni motor tuning and racing

Based on your comments in the first mail, am I correct in thinking you want to run 2 motors in parallel but use only one controller ? Have you considered (electrically) separating the motors by using two controllers ? The the (small) difference in rpm/V wouldn't really matter. Even nicer would be to...
by Lebowski
Jul 07 2011 1:05am
Forum: E-Bike Technical
Topic: Timing Adjustment Tool
Replies: 461
Views: 61067

Re: Timing Adjustment Tool

Ok, so the 3 pin devices you have in your motor are actually fully integrated circuits containing the actual Hall sensor, an amplifier and probably some sort of schmidt trigger (to give it hysteresis). The sensor itself (a small part of the internals of your 3 pin device) is actually 4 pins. To oper...
by Lebowski
Jul 06 2011 2:32pm
Forum: E-Bike Technical
Topic: Timing Adjustment Tool
Replies: 461
Views: 61067

Re: Timing Adjustment Tool

Arlo1 wrote:They are three wire halls and trying to do what your are describing would be very time consuming so would be very stupid!
Thank you for calling my idea stupid, I can see you gave it a lot of thought.
Do you actually know how a hall effect sensor works or what a current source is ?
by Lebowski
Jul 06 2011 12:43pm
Forum: E-Bike Technical
Topic: Timing Adjustment Tool
Replies: 461
Views: 61067

Re: Timing Adjustment Tool

A small question on the hall sensors used in combination with sensored controllers... are the hall sensors the very basic 4 pins analog type or do they have added electronics in them to provide an amplified or digital signal ? If its the basic 4 pin type, have you thought of applying a small bias cu...
by Lebowski
Jul 05 2011 5:43am
Forum: Motor Technology
Topic: Updated Cap choices for high power motor controllers Updated
Replies: 92
Views: 31987

Re: Updated Cap choices for high power motor controllers Upd

I would love to see someone start a controller build thread that outlines each component chosen, why this particular choice over others, and what each part does in the system. How large would the interest be for a thread outlining the design (from scratch) of a sensorless BLDC controller ? I have a...
by Lebowski
Jul 05 2011 1:14am
Forum: E-Bike Technical
Topic: Timing Adjustment Tool
Replies: 461
Views: 61067

Re: Timing Adjustment Tool using a microcontroller

There's no *technical* reason the ESC couldn't be reprogrammed to do this work by itself, as part of normal operation as a controller. But it is highly unlikely that you'd be able to get the source code for the ESC from the manufacturer so you could rewrite it to do so. That would require writing t...
by Lebowski
Jun 29 2011 3:17am
Forum: Battery Technology
Topic: Balance charging with DC/DC converters?
Replies: 4
Views: 650

Re: Balance charging with DC/DC converters?

The schematic you've drawn will work but only when the inputs and outputs of the DCDC converter are isolated. The DCDC converters you bought, is the ground of input and output the same ? If so you're scheme will not work as you'll short out the cells. You need to determine which type of dcdc convert...
by Lebowski
Jun 29 2011 2:44am
Forum: General Discussion
Topic: emp proof ebike?
Replies: 28
Views: 3528

Re: emp proof ebike?

on a similar note, my girlfriend chickened out as testpilot when I told here my bike's engine runs on a very high
voltage and that it uses a circuit similar to what's used in a car to generate sparks :mrgreen:
by Lebowski
Jun 29 2011 1:59am
Forum: General Discussion
Topic: emp proof ebike?
Replies: 28
Views: 3528

Re: emp proof ebike?

You really want something metal like a bike close to your family jewels in the event of an EMP ?

Fine by me though :mrgreen: just more 'work' for me when we need to re-populate the earth 8)
by Lebowski
Jun 28 2011 1:50am
Forum: Motor Technology
Topic: ES DIY Motor Challenge
Replies: 324
Views: 101000

Re: ES DIY Motor Challenge

:D I just found this forum :D As a hobby project I've been building my own bicycle engine and engine controller (both from scratch using of the shelf stuff like magnets, an iron bar and some sheets of aluminium and using only tools like a simple drill and a jigsaw). http://www.youtube.com/watch?v=dG...